Some hopeful news in the battle against HIV: a daily pill shows promise in preventing transmission of the virus. So much promise, in fact, that scientists stopped the trial so they could start giving the pills to the control group as well.

According to the AP, two studies have come up with good news for the drug Truvada. In one, men and women taking the pill saw a 78% reduction in their HIV risk. Another looked at heterosexual couples in which one partner already had the virus — uninfected partners taking Truvada were 73% less likely to get HIV than those taking a placebo. Outside reviewers decided these results were so compelling that it would be unethical to keep giving the control group dummy pills, and researchers are now offering Truvada to all participants.

Truvada is already in use as a treatment for HIV, but past trials of the drug as a preventive measure have yielded mixed results. A study of gay men last year was encouraging, but another study released in April found no benefit for women taking the pill. Researchers aren't sure about the reason for the discrepancy, but speculate that the women may not have been taking the pill often enough. They remain hopeful about the future of Truvada, especially now that manufacturer Gilead Sciences has announced it will allow production of generic versions of drugs, making it more affordable. Truvada's success comes on the heels of news that antiretroviral drugs can greatly reduce transmission rates if infected people start taking them right away. Researchers appear to be making strides in slowing down transmission of the virus — sadly, a true cure remains out of reach for now.